This Email Service allow you to send emails from your asp.net application (webforms or mvc) with easy configuration steps, you can use it in the registration process to send emails to your users and customers or when you want to send automated newsletters

First of all you need to get new API Key by registering & confirming your email in Zender

In your Visual Studio project, Install the package from Nuget. This package will add a reference to Zender.Mail in your .NET application. Zender.Mail is the client library that is built to consume Zender Web API (Alternatively, you can also download and add the Zender.Mail.dll (1.0.0.0) reference manually):

Within the first three months of using Zender’s Marketing tool, TestingMom.com increased its open rates by 17%, enhanced its delivery rate by 14%, and decreased its unsubscribe rate by 96%. McCurdy even estimates that about 40% of the brand’s conversions now come from email.